In present foundry practice, moulds are made in a number of ways, including the production of green sand moulds and the production of "shell moulds". However, despite long acceptance and continuous refinement, including in recent years various approaches designed to automate such practices, the practices of the prior art have had a number of drawbacks, and these have become more critical in recent years because of the need for improving working conditions in the foundries and the need to make moulds more rapidly with a lower manpower requirement.
Much of the requirement for foundry moulds has .[.here tofore.]. .Iadd.heretofore .Iaddend.been met by making green sand moulds, following procedures usually requiring use of sea coal and providing a mould which is not cured in the sense that it has adequate strength to allow extensive handling. The use of .[.seal.]. .Iadd.sea .Iaddend.coal has always been objectionable because that material is dirty, contributing a great part, if not the primary part, of the dirt common in foundries today. The weak, uncured nature of green .[.snad.]. .Iadd.sand .Iaddend.moulds has also been a seriously limiting factor, even in the recently developed automatic moulding systems, since such moulds cannot be handled extensively or transported in the usual sense, as by trucks and the like, and the green sand moulds therefore must be made at the location where they are to be used. The practice of using green sand moulds has other disadvantages, including limitations on the dimensional accuracy of the moulds, the need for metal moulding flasks to prevent metal run-out, a relatively high time and labor requirement in mould production, excessive raw material storage requirements, including storage for sea coal, and excessive sand burn-on during casting, with attendant excessive time requirements in the cleaning room.
While shell mould practices offer some advantages, including elimination of sea coal and the production of moulds which are cured and therefore have .[.adeuqate.]. .Iadd.adequate .Iaddend. strength to withstand considerable handling, shell moulds have only a relatively limited applicability and cannot be adopted as an extensive replacement for green sand moulds and are subject to the disadvantages of high pattern time and cost and the tendency for the shell mould itself to warp.
The method disclosed in our aforementioned copending application provides for high rate, automated production from dry sand formulations of fully cured foundry moulds, avoiding the use of sea coal and other objectionable ingredients, with the cured moulds having greater dimensional accuracy and being sufficiently strong to withstand handling and transportation, the moulds requiring less sand and shorter and easier operations in the cleaning room than is the case with castings from green sand moulds. A general object of the present invention is to provide apparatus for carrying out that method.
Another object is to provide a mould pressing apparatus wherein operation of the apparatus to shape a portion of a bed of sand mix according to a pattern also serves to sever the pressed mould part from the bed of sand mix.
A further object is to devise such an apparatus including means for curing the pressed mould parts.
Still another object is to provide an apparatus capable of shaping and curing mould parts on a continuous, automated, high rate basis.